Mobile telephones and other such mobile communication devices are typically assigned a unique identity at manufacture. For example, all communication devices capable of communicating with a GSM or 3G network have a unique international mobile equipment identity (IMEI) number. For GSM and 3G devices the GSM association allocates IMEI numbers to device manufacturers. The IMEI information is maintained in a global IMEI database (IMEI DB), formerly known as the central EIR (CEIR), and is made available to all GSM and 3G network operators.
Additionally, each network operator maintains their own equipment identity register (EIR). An EIR enables a network operator to maintain a so-called blacklist of GSM or 3G devices that should be denied service on mobile networks because they have been reported as lost, stolen, faulty, or otherwise unsuitable for use.
The IMEI DB also maintains a blacklist that is updated regularly from the EIRs of participating GSM and 3G network operators. This in turn enables each network operator to update their own EIRs with the global blacklist of devices. In this way, each EIR is able to deny service to any device on the global blacklist.
However, as the number of network operators who provide their EIR blacklist to the IMEI DB, so the size of the IMEI DB blacklist grows. Consequently, when a network operator wishes to download the global IMEI DB blacklist, huge amounts of data are involved.
Accordingly, one aim of the present invention is to overcome, or at least alleviate, at least some of the problems of the prior art.
According to a first aspect of the present invention there is provided a method of controlling access to a communication network, comprising receiving a request from a communication device to connect to the communication network, the request including a substantially unique identifier of the device, and determining whether the identifier is contained in a local device database of the network. Where it is determined that the identifier is not contained in the local database the method further comprises authorizing the device to connect to the network, and at a subsequent update of the local device database, determining the status of the identifier from a shared device database, and updating the status of the determined identifier in the local device database with the determined status.
Suitably, the local database comprises identifiers of devices authorized to connect to the network and identifiers of devices not authorized to connect to the network, the step of authorizing comprising determining whether the received identifier is authorized to connect to the network.
Suitably, the method further comprises, where an identifier is not contained in the local database, marking the identifier such that the status thereof is subsequently retrieved from the shared device database.
Suitably, the local database comprises a white-list of device identifiers authorized to connect to the network, a black list of device identifiers not authorized to connect to the network, and a gray-list of device identifiers authorized to connect to the network but to be monitored, the step of authorizing comprising determining whether the device is authorized to connect to the network by way of the identifier.
Suitably, where the identifier is not contained in the local database, the method further comprises adding the identifier to the gray-list of the local database.
Suitably, during the update of the local device database, the method further comprises updating the status of any gray-listed devices with the status stored in the shared device database.
Suitably, the method is adapted for use for with a mobile telecommunication network.
Suitably, the method is adapted for use with a GSM or 3G telecommunications network, the device identifiers being international mobile equipment identity numbers, the local database being an equipment identity register and the shared database being a global IMEI database.
According to a second aspect of the present invention, there is provided a communication system operable in accordance with any of above-mentioned method steps.